Method of treating separators



Patented Dec. 22, 1925.

UNITED STATES PATENT OFFlCE.

RUFUS ,N. CHAMBERLAIN, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO GOULD STORAGE BATTERY COMPANY, INC., OF NEW YORK, N. Y., A COR- PORATION OF NEW YORK.

METHOD OF TREATING SEPARATORS.

N 0 Drawing.

To all whom it may concern Be it known that I, RUFUS N. CHAMBER- LJXJN, a citizen of the United States, residing at Chicago, county of Cook, State of Illinois, have invented a new and useful Improvement in Methods of Treating Separators, of which the following is a full, clear, and exact description.

My invention relates to a method of treat ing storage battery separators. Separators have been treated heretofore with acid resistant material to retard the action of the electrolyte thereon. Processes for so treating separators are set forth in my Patents No. 1,194,818, August 15, 1916. and No. 1,328,420 January 20, 1920, and in my Patent No. 1,490,204, April 15, rear. Either of the processes set forth in said patents may be used in connection with my present invention.

After the separatorshave been treated in accordance with one of the above processes, it is further treated to increase its conductivity without affecting its acid resistant qualities.

In carrying out my present process the separators are treated so as to thinly coat the interior fibrous structure of the separators with an acid resistant material, such as parafline, rubber or an oil, such as linseed oil. Many other acid resistant materials may be used. In the preferred form a solvent-carrier is used which acts as a vehicle to carry the particles of acid resistant material in to the separator structure and deposit the same on the fibres of the separator. The solvent is then driven off leaving a thin coating of acid resistant material uniformly distributed over the interior fibrous structure of the separator. The foregoing treatment produces a separator of many superior qualities, but the thin layer of acid resistant material unavoidably slightly affects the porosity of the separator and correspondingly decreases its conductivity. In my above mentioned Patent No. 1,490,204 I have set forth a step in the process of treating separators consisting in subjecting the separators after they have been treated with an acid resistant material to a liquid at a temperature of about 200 F. When the separators are thus treated with water as the liquid the initial conductivity of the separators is materially increased provided the separa- Application filed. March 24, 1922. Serial No. 546,477.

I have discovered that the initial and subsequent conductivity of the separators may be greatly increased by subjecting the separators which have been treated with an acid resistant material to an alkaline solution at a temperature substantially higher than that to which the separators are subjected in service. This temperature is preferably about the boiling point of the solution. The solution may vary considerably in strength and many different alkalis may be used in the solution. The strength of the solution and the particular chemical may depend upon conditions which will be pointed out later. I have found that a bath of 1% to 2% solution of washing soda or a 1% to 2% solution of caustic soda is very effective in the ordinary case. The percentage of alkali in either case may vary from one-quarter of 1% to 10% or more. The strength of the treating solution will depend roughly upon the amount of acid resistant material with which the separators are impregnated in the J first place.

\Vhile I do not know the exact action which the solution has upon the treated separators, nevertheless, in my opinion, the solution has the effect of dissolving certain constituents of the fibers so as to partially reopen the pores or passages through the separator which have been somewhat closed by the treatment with the acid lesistant material. It may be that some of the cells, it a wood separator is being treated, are opened by the expansion of the gas contained in the cells due to the increased temperature of the solution. I have found. however, that by the use of a solution. such as that described, instead of water a marked increase in condin-livity is secured when applied at the same temperature so that apparently the action of the alkali has a material effect upon the separator resulting in a substantially higher conductivity. By the use of the alkaline solution the conductivity of the separator is increased about 25% to 50% as compared with a separator which has not been subjected to the heat treatment. The increase in conductivity depends upon the strength of the solution and also upon the temperature. From tests which I have made it seems apparent that the benefits result from the l chemical action of the alkali, the temperature to which the solution is heated and that the activity of thechemical is .alsoincreased by the temperature so that both the temperature and "the strength of the solution are important ,factors in the method. a

, lVhile I prefer to use an alkali as the chemical, I have found that aWeak acid I may be used with good effect, and therefore I do'i n'ot de'sire to limit my invention :to the use-of alkalis, asthe'employment of a Weak acid at the temperature employed has the effect' or producing substantial benefits. "Among the chemicals which may be 'used 7 may beinentioned carbonate 'or bicarbonate of soda, caustic soda,- caustic; potash or other c'l1eniicalagents which have awsi-milar effect upon Wonder similar fibers, and Weak acid.

Mafi-y'variations may be made in the strengthefthe solution and also in the temperatitre. For instance, :allovver temperatunemighc be used vvith a correspondingly strongersolution and vice versa and in many -'-instances the'str'ength of the solution and the temperature will depend somewhat upon the amount of acid resistant material 7 which has been previously applied to the qseparator. Y

relaims" I 1. The method which consists 'in tr'eating aseparator with an acidresistant material and subjecting the-treated separator to the action of an alkali at high temperature,

substantially as described.

' 1 ".-2.'-The method or t-reatinea :"fibrous protective action of an acid resistant The method of treating a fibrous separator which consists 'in treating the separator with an :acid resistant material and treating said separator to partially re store its original conductivity, substantially as described; 7 Q j 4E. The method which consists in impregnating a' separator with a protective material in solution and subjecting said a separator to an alkaline solution to increase the oOl lclll'Ct-lvlty of the treated separator, substantially as described. I

'5; The method which consists in impregnatinga separator With rubber in solution, drivingofi' the solventand subjecting said separator to ahot, alkaline solution, sub

stantia'lly-as described. 7 7

consists in'iIn-preg- 6; 7 The method Which natingaseparator With rubber insolution,

and "subjecting said separator 'to a hot alkaline-solution,- substantially as described. -7. The method which consists in impreg- Hating a separator 'With'frubber in solution, and sub ecting said separator to an all'i ahne solutionatapproxima'tely 212? F., substa-ntially as described. a I V e In testimony whereof I have hereunto set my'hand. I

I R E CHAMBERLAIN. i 

